Ammonia Decomposition in the Process Chain for a Renewable Hydrogen Supply

Abstract

This review article deals with the challenge to identify catalyst materials from literature studies for the ammonia decomposition reaction with potential for application in large-scale industrial processes. On the one hand, the requirements on the catalyst are quite demanding. Of central importance are the conditions for the primary reaction that have to be met by the catalyst. Likewise, the catalytic performance, i.e., an ideally quantitative conversion, and a high lifetime are critical as well as the consideration of requirements on the product properties in terms of pressure or by-products for potential follow-up processes, in this case synthesis gas applications. On the other hand, the evaluation of the multitude of literature studies poses difficulties due to significant varieties in catalytic testing protocols.

Thermocatalytic Ammonia Decomposition – Status and Current Research Demands for a Carbon‐Free Hydrogen Fuel Technology

“…Equilibrium conversion of ammonia at ambient pressure based on thermodynamic data reaches 95 % and 99.5 % at 573 K and 723 K, respectively [37] . Thus, moderate to high reaction temperatures (≥400 °C, but frequently 600 °C) are required for sufficient hydrogen generation [2] . At these temperatures, the dissociation reaction is usually kinetically limited.…”

“…As of today, ammonia decomposition for the generation of CO x ‐free hydrogen is a highly researched field. Stable and efficient heterogeneous catalysts are in high demand considering possible applications in industry and energy infrastructure [2] . Yet, the interaction between different adsorption and desorption sites on ammonia decomposition catalysts are not completely understood.…”

“…[37] Thus, moderate to high reaction temperatures (� 400 °C, but frequently 600 °C) are required for sufficient hydrogen generation. [2] At these temperatures, the dissociation reaction is usually kinetically limited. So far, very few catalyst systems are able to achieve these high values of conversion.…”

“…Moreover, the timely replacement of dwindling fossil fuel reserves with more sustainable and environmentally friendly alternatives will determine the future of humanity. Hydrogen generated from water electrolysis is a cornerstone of future energy applications, which is conveniently highlighted as “hydrogen economy” [2] . On one hand, hydrogen is a key raw material in chemical industry for a series of essential processes (i. e., production of NH 3 , methanol, in hydrocracking of oil etc.).…”

“…Hydrogen generated from water electrolysis is a cornerstone of future energy applications, which is conveniently highlighted as "hydrogen economy". [2] On one hand, hydrogen is a key raw material in chemical industry for a series of essential processes (i. e., production of NH 3 , methanol, in hydrocracking of oil etc.). On the other hand, it has also been established as a suitable fuel through the use of low-temperature hydrogen fuel cells.…”